(a) Field of the Invention
The present invention relates to an improved structure for a turbo blower, and more particularly to a turbine blade which enables power consumption to automatically decrease when an air inlet end or air outlet end of the turbine is obstructed, thereby reducing motor load.
(b) Description of the Prior Art
FIG. 7 shows a turbine of a turbo blower of prior art primarily structured to include a plurality of radially arranged guide vanes b between a circular base plate a and a top plate a′. The radially arranged guide vanes b extend radially outward from close to the center of the base plate a towards the outer edge of the base plate a. Front vane ends b1 of the guide vanes b are positioned close to the center of the base plate a, the upper edge of each guide vane b forms a curve by gradually decreasing the height of the guide vane b from the front vane end b1 to the lowest point at a vane rear end b2, whereat the height of the guide vane b extends horizontally outward. The turbine is disposed in an air hood c, and a motor d directly or indirectly drives and rotates the turbine. The air hood c is provided with an air inlet c1 and an air outlet c2, wherein the air inlet c1 is located above a corresponding center portion (rotating center) of the turbine, and a circular hole al′ is correspondingly defined in the turbine top plate a′. The air outlet c2 is correspondingly located on the outer edge of lateral to the turbine, thereby enabling air to be expelled from the air outlet c2 after being sucked into the turbine from the air inlet c1.
According to the aforementioned structure, a cylindrical space is formed by the front ends b1 of the guide vanes b to a center point when the motor d is driving and rotating the turbine at high speed, and a vacuum negative pressure is created within the cylindrical space, thereby enabling outside air to be sucked into the air inlet c1, whereafter the guide vanes b push the sucked-in air towards the rear ends b2 at the outer edges of the guide vanes b. The vane rear ends b2 of the guide vanes b then compresses the air to produce positive air pressure, which is then expelled through the air outlet c2.
However, the height of the vane rear ends b2 of the guide vanes b is relatively low (that is, effective area for wind shear is relatively small), a consequence of which easily results in an inadequate positive pressure to discharge air in the turbine of prior art turbo blowers. Such an undue prior art structure is acceptable for application in situations where air intake and air discharge requirements are not so stringent, for example, simple daily appliances, such as a vacuum cleaner, blast furnaces, and so on. Nevertheless, the turbo blower of prior art is inapplicable in situations where high pressure air is required because of the substantially large difference in value between negative pressure and positive pressure at the two ends when one end of the air inlet c1 or the air outlet c2 is obstructed, and thus, a multiple increase in rotating power driving the turbine results, a consequence of which gives prior art the shortcoming of increasing motor load that might easily cause the turbine to burn out.